1. Technical Field
The present invention relates to a compressed gas storage system in which a solenoid valve is incorporated in a gas tank which stores therein compressed gas.
2. Related Art
A compressed gas storage system is such as to be installed on, for example, a motor vehicle, and in the system, a solenoid valve is incorporated in a gas tank which stores therein compressed gas, and compressed gas is supplied by opening the solenoid valve within the gas tank (for example, JP-T-6-508422 (page 6, FIGS. 2, 3) (the term “JP-T” as used herein means a published Japanese Translation of a PCT patent application) which is referred as Patent Document No. 1).
Patent Document No. 1 will be described based on the following drawing.
FIGS. 8(a), 8(b) are drawings which explains a basic configuration of the related art, and a related art anti-collision electromagnetic valve or solenoid valve 101 for a natural gas-driven passenger vehicle includes a main valve element 104 mounted on a collar 103 of a pressure vessel 102, a fill port 105, a feed-through hole 106 and an outlet port 107 which are formed in the main valve element 104, a central flow communication passage 108 and a solenoid poppet valve assembly 109 which is screwed into the pressure vessel 102 at a central portion thereof for connection with the main valve element 104.
The solenoid poppet valve assembly 109 has a solenoid 111, a seal 112 and a passage 113, and since the seal 112 is separated when the solenoid 111 is energized, natural gas flows to the engine side through the passage 113, the flow communication path 108, and the outlet port 107 (an outlet coupling 114).
In the anti-collision solenoid valve 101 described in Patent Document No. 1, however, when the solenoid 111 is energized to separate the seal 112 so as to allow natural gas to flow out, the temperature of natural gas so flowing out decreases due to Simon expansion, and since the seal 112 is cooled by the natural gas which flows out, the temperature of the seal 112 is decreased, whereby the sealing property resulting when the solenoid valve 101 is closed is decreased.
Then, to cope with this, although it is considered, for example, to change the material of the seal 112 to a special material which can deal with low temperatures or to heat the portion of the solenoid poppet valve assembly 109 which is screwed into the collar 113 of the pressure vessel 102, it is difficult to transfer heat as deep as the seal 112, and on the other hand, there has been a demand for a construction which can deal with the problem without using special materials.